1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
|
/*
* TLS Server Hello and Server Hello Done
* (C) 2004-2011,2015,2016,2019 Jack Lloyd
* 2016 Matthias Gierlings
* 2017 Harry Reimann, Rohde & Schwarz Cybersecurity
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/tls_messages.h>
#include <botan/tls_extensions.h>
#include <botan/tls_callbacks.h>
#include <botan/internal/tls_reader.h>
#include <botan/internal/tls_session_key.h>
#include <botan/internal/tls_handshake_io.h>
#include <botan/internal/tls_handshake_hash.h>
#include <botan/internal/stl_util.h>
namespace Botan {
namespace TLS {
namespace {
const uint64_t DOWNGRADE_TLS11 = 0x444F574E47524400;
//const uint64_t DOWNGRADE_TLS12 = 0x444F574E47524401;
std::vector<uint8_t>
make_server_hello_random(RandomNumberGenerator& rng,
Protocol_Version offered_version,
const Policy& policy)
{
BOTAN_UNUSED(offered_version, policy);
auto random = make_hello_random(rng, policy);
return random;
}
}
// New session case
Server_Hello::Server_Hello(Handshake_IO& io,
Handshake_Hash& hash,
const Policy& policy,
Callbacks& cb,
RandomNumberGenerator& rng,
const std::vector<uint8_t>& reneg_info,
const Client_Hello& client_hello,
const Server_Hello::Settings& server_settings,
const std::string next_protocol) :
m_version(server_settings.protocol_version()),
m_session_id(server_settings.session_id()),
m_random(make_server_hello_random(rng, m_version, policy)),
m_ciphersuite(server_settings.ciphersuite()),
m_comp_method(0)
{
if(client_hello.supports_extended_master_secret())
m_extensions.add(new Extended_Master_Secret);
// Sending the extension back does not commit us to sending a stapled response
if(client_hello.supports_cert_status_message() && policy.support_cert_status_message())
m_extensions.add(new Certificate_Status_Request);
const auto c = Ciphersuite::by_id(m_ciphersuite);
if(c && c->cbc_ciphersuite() && client_hello.supports_encrypt_then_mac() && policy.negotiate_encrypt_then_mac())
{
m_extensions.add(new Encrypt_then_MAC);
}
if(c && c->ecc_ciphersuite() && client_hello.extension_types().count(TLSEXT_EC_POINT_FORMATS))
{
m_extensions.add(new Supported_Point_Formats(policy.use_ecc_point_compression()));
}
if(client_hello.secure_renegotiation())
m_extensions.add(new Renegotiation_Extension(reneg_info));
if(client_hello.supports_session_ticket() && server_settings.offer_session_ticket())
m_extensions.add(new Session_Ticket());
if(!next_protocol.empty() && client_hello.supports_alpn())
m_extensions.add(new Application_Layer_Protocol_Notification(next_protocol));
if(m_version.is_datagram_protocol())
{
const std::vector<uint16_t> server_srtp = policy.srtp_profiles();
const std::vector<uint16_t> client_srtp = client_hello.srtp_profiles();
if(!server_srtp.empty() && !client_srtp.empty())
{
uint16_t shared = 0;
// always using server preferences for now
for(auto s_srtp : server_srtp)
for(auto c_srtp : client_srtp)
{
if(shared == 0 && s_srtp == c_srtp)
shared = s_srtp;
}
if(shared)
m_extensions.add(new SRTP_Protection_Profiles(shared));
}
}
cb.tls_modify_extensions(m_extensions, SERVER);
hash.update(io.send(*this));
}
// Resuming
Server_Hello::Server_Hello(Handshake_IO& io,
Handshake_Hash& hash,
const Policy& policy,
Callbacks& cb,
RandomNumberGenerator& rng,
const std::vector<uint8_t>& reneg_info,
const Client_Hello& client_hello,
Session& resumed_session,
bool offer_session_ticket,
const std::string& next_protocol) :
m_version(resumed_session.version()),
m_session_id(client_hello.session_id()),
m_random(make_hello_random(rng, policy)),
m_ciphersuite(resumed_session.ciphersuite_code()),
m_comp_method(0)
{
if(client_hello.supports_extended_master_secret())
m_extensions.add(new Extended_Master_Secret);
if(client_hello.supports_encrypt_then_mac() && policy.negotiate_encrypt_then_mac())
{
Ciphersuite c = resumed_session.ciphersuite();
if(c.cbc_ciphersuite())
m_extensions.add(new Encrypt_then_MAC);
}
if(resumed_session.ciphersuite().ecc_ciphersuite() && client_hello.extension_types().count(TLSEXT_EC_POINT_FORMATS))
{
m_extensions.add(new Supported_Point_Formats(policy.use_ecc_point_compression()));
}
if(client_hello.secure_renegotiation())
m_extensions.add(new Renegotiation_Extension(reneg_info));
if(client_hello.supports_session_ticket() && offer_session_ticket)
m_extensions.add(new Session_Ticket());
if(!next_protocol.empty() && client_hello.supports_alpn())
m_extensions.add(new Application_Layer_Protocol_Notification(next_protocol));
cb.tls_modify_extensions(m_extensions, SERVER);
hash.update(io.send(*this));
}
/*
* Deserialize a Server Hello message
*/
Server_Hello::Server_Hello(const std::vector<uint8_t>& buf)
{
if(buf.size() < 38)
throw Decoding_Error("Server_Hello: Packet corrupted");
TLS_Data_Reader reader("ServerHello", buf);
const uint8_t major_version = reader.get_byte();
const uint8_t minor_version = reader.get_byte();
m_version = Protocol_Version(major_version, minor_version);
m_random = reader.get_fixed<uint8_t>(32);
m_session_id = reader.get_range<uint8_t>(1, 0, 32);
m_ciphersuite = reader.get_uint16_t();
m_comp_method = reader.get_byte();
m_extensions.deserialize(reader, Connection_Side::SERVER);
}
/*
* Serialize a Server Hello message
*/
std::vector<uint8_t> Server_Hello::serialize() const
{
std::vector<uint8_t> buf;
buf.push_back(m_version.major_version());
buf.push_back(m_version.minor_version());
buf += m_random;
append_tls_length_value(buf, m_session_id, 1);
buf.push_back(get_byte<0>(m_ciphersuite));
buf.push_back(get_byte<1>(m_ciphersuite));
buf.push_back(m_comp_method);
buf += m_extensions.serialize(Connection_Side::SERVER);
return buf;
}
bool Server_Hello::random_signals_downgrade() const
{
const uint64_t last8 = load_be<uint64_t>(m_random.data(), 3);
return (last8 == DOWNGRADE_TLS11);
}
/*
* Create a new Server Hello Done message
*/
Server_Hello_Done::Server_Hello_Done(Handshake_IO& io,
Handshake_Hash& hash)
{
hash.update(io.send(*this));
}
/*
* Deserialize a Server Hello Done message
*/
Server_Hello_Done::Server_Hello_Done(const std::vector<uint8_t>& buf)
{
if(buf.size())
throw Decoding_Error("Server_Hello_Done: Must be empty, and is not");
}
/*
* Serialize a Server Hello Done message
*/
std::vector<uint8_t> Server_Hello_Done::serialize() const
{
return std::vector<uint8_t>();
}
}
}
|
